The present application relates generally to a device for precisely metering fluids, more particularly the application discloses a microfluidic device including a micro-aliquotter.
Microfluidic devices are useful in various applications and can be used to analyze small amounts of samples in fluid systems for contaminants, chemicals, or other analytes in the body, water systems, industrial fluid systems, or any of a variety of systems having fluid components. In many of these microfluidic based analytical systems, precise volumes of reagents and/or analytes are required. It may also be the case that these volumes be kept very small, especially in situations where the reagents may be expensive, the sample is limited or the physical space inside the analyzer is limited.
Basically, in microscale analytical systems, the precise metering of small fluid volumes is important to obtaining reliable results, and arguably, may be the most important internal function of such a system. Accordingly, there is a need for integrated fluid aliquotting devices with improved precision in metering and dispensing fixed and variable volumes of fluid in a microfluidic device. Applicant has developed a micro-aliquotter that can dispense a fixed or variable volume of fluid with improved precision. The variable volume is possible because an elastic film is used that expands in response to the fluid pressure of a fluid building up and being contained under the film and between the film and a rigid, dimensionally stable surface. Depending upon the fluid pressure applied and the time the fluid pressure is applied for a fluid, the elastic film will expand to a particular volume that can be determined in reference to a calibration curve of the micro-aliquotter for that fluid. The calibration may depend upon the fluid being aliquoted, the pressure used to move the fluid, the amount of time the pressure is applied and the mechanical characteristics of the elastic member.
Because the fluid volume inside the aliquotter is formed with the help of an elastic member, it represents a fluidic structure the volume of which can be operationally defined from essentially zero up to the designed limit. This inherent feature allows the fluidic system, in general, to be more conservative of fluids, since no additional fluid movement is required to displace the resulting aliquoted volume.